Safety in the process industries
01 March 2010
Ian Curtis urges the guardians of safety control systems deployed in the process industries to embrace technology that is designed to make their lives easier
There can be no compromise on safety within an industrial environment. A simple and stark statement, but one that presents many challenges to those working everyday with potentially hazardous processes.
Experience of working with the IEC61508 and IEC61511 safety standards varies widely. Many companies will have ‘tried and tested’ safety management systems that undergo constant review and refinement whilst others will have less experience because their exposure to safety instrumented system (SIS) deployment experience is less frequent.
So, what are the current technological trends that are helping set the safety system agenda?
As international standards, such as IEC 61511, place emphasis on a Safety Life Cycle (SLC) approach, we are starting to see a move towards the development of supportive safety lifecycle tools. The traditional Cause & Effect Matrix (CEM) approach for documenting and defining safety logic is well established, but a move toward additional system lifecycle tools to aid the engineering community should prove beneficial.
Such planning tools allow the engineer to document the CEM logic required for a SIS in a form that will be familiar to them but with the subsequent automatic creation of associated code in the SIS and testing and commissioning using the same CEM format for visualisation.
This approach can remove the possibility of human error and misinterpretation, and will inherently reduce systematic errors. The enhanced functionality of such tools not only creates the logic in the system controller but also generates the operator interface along with the mechanisms for implementing overrides and bypasses in a controlled manner.
The recognised safety standards call for separation of process control and process safety - traditionally achieved by a combination of physical separation and diverse systems, often from separate suppliers. Increasingly, companies are seeking the benefits of a more integrated approach, which include a reduction in spare parts, reduced training, simplified engineering and a more consistent, single window operator view on the process.
End users have already discovered the benefits of fieldbus within process control systems, and the move towards enjoying similar benefits with safety instrumented systems is well underway. The big benefits are operations and maintenance savings made available through advanced diagnostics and asset management tools. Using digital platforms, users are continuously able to assess information in intelligent SIS components and analyse safety performance. In addition, they have access to data and diagnostic information that is essential for all testing, whether automatic or planned. As with non-safety fieldbus implementation, the information benefits and reduced costs associated with installation, maintenance and testing will ensure this technology gains wider acceptance.
Process accidents can have terrible consequences. People lose their lives or suffer horrible injuries. Families and communities are devastated. Adopting and maintaining best practice in safety management, implementing a strong safety culture and conforming to current process safety standards is a major challenge for industry. The technology trends are seeking to make this challenge easier to meet; they will become the safety system norm, not the exception, in the years to come.
Ian Curtis is a safety consultant with Siemens Industry Automation
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